<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<style>
.block{
position:absolute;
height:100px;
width:100px;
display:none;
background:blue;
}
</style>
</head>
<body>
<button>Click me!</button>
<div class="block">1</div>
<div class="block">2</div>
<div class="block">3</div>
<div class="block">4</div>
<div class="block">5</div>
<div class="block">6</div>
<div class="block">7</div>
<div class="block">8</div>
<div class="block">9</div>
<div class="block">10</div>
<script>
var block = document.querySelectorAll('.block');
document.querySelector('button').onclick = function(){
var rnd = Math.floor(Math.random() * 10);
block[rnd].style.display = 'block';
setTimeout(()=>{
block[rnd].style.display= '';
},1000); //время
};
</script>
</body>
</html>